Trudy, and all, 2 years on and I've now found one of the same vases as yours and Ed's and it is not the same as the ones Della and Chris showed by Luminarc. Mine is also 22cm tall, weighs 1001g, and has no mark for France anywhere on it. So whatever they are, they are not the aforementioned Luminarc vases.

Just to throw something else into the mix. I have a very similar vase marked France and 18 on a bird bath bottom, and it's triangular. Variation by same maker or a popular style adapted by a number of makers?